The invention relates to switch assemblies. More particularly, a modular reed switch assembly and method for making utilizes a compliant material that is able to dampen vibrations seen by the reed switch. This helps reduce reed switch failures due to high vibration levels and other environmental factors.
There are many commercial and military applications of reed switches. One specific application is the use of a reed switch to provide valve position feedback information on aircraft. However, a known problem with reed switches is a predisposition towards failing in the high vibration environments that aircraft encounter during operations. Rotating equipment such as motors, engines, actuators and gearing can all generate vibrations and introduce other harmonic disturbances that can cause numerous problems with reed switches and cause them to fail. Deleterious consequences such as switch bounce and hot latching are very environmentally sensitive phenomena, where small changes in response characteristics or differing vibration inputs can significantly affect ultimate performance.
One particular application of the reed switch is to provide a positive indication of the status (e.g., open or closed) of a fuel valve that regulates the flow of fuel to an engine. If mechanical latching or sticking occurs between the electrical contacts of a reed switch, an indicator may yield a faulty reading indicating a disagreement or mismatch between an intended command and a valve position.
Therefore, it is desirable to have a reed switch assembly that can operate in hostile environments and eliminate or reduce the harmful effects of the operational environment, such as vibration, upon reed switch operation.
In accordance with the present invention, the deficiencies in prior systems are overcome by providing an improved modular reed switch assembly and a method for making the same.
A modular reed switch assembly includes a reed switch that is enclosed between a secondary reed switch cover and a reed switch base. The reed switch base is recessed to accommodate the reed switch. The reed switch is further enclosed between a primary reed switch cover and a main housing wherein the primary reed switch cover and the main housing are recessed to accommodate the switch assembly containing the reed switch. A protrusion provides access to the electrical contacts of the reed switch through the primary and secondary reed switch covers.
The secondary reed switch cover and the reed switch base snap together around the reed switch. The mating surfaces of the secondary reed switch cover and the reed switch base snap together and form an integrated whole surrounding the reed switch. The material used to enclose the reed switch is compressed upon installation around the reed switch. The material used to enclose the reed switch is a compliant material and has a durometer rating. The material selected can be Viton(copyright) or Fluorosilicone(copyright). The material used, as well as any rubber used, yields durometer value (D) ranges from a high value of about 75 D average to a low value of about 55 D average.